Question

  Average values of effective coefficient of friction for bearings are described below:

1. Spherical ball bearing – f₁     

2. Cylindrical roller bearing – f₂

3. Taper roller bearing – f₃

4. Stable (thick film) sliding – f₄

          Contact bearing

(a) f₁<f₂<f₃<f₄                (b) f₁<f₂<f₄<f₃

(c) f₂< f₁<f₃<f₄               (d) f₁<f₄<f₂<f₃